I. Background of the Invention
II. Summary of the Invention
III. Brief Description of the Figures
IV. Detailed Description of the Invention
A. Definitions
B. Stimulation of CTL and HTL responses against HBV
C. Immune Response Stimulating Peptides
1. Binding Affinity of the Peptides for HLA Molecules
2. Peptide Binding Motifs and Supermotifs
a) HLA-A1 supermotif
b) HLA-A2 supermotif
c) HLA-A3 supermotif
d) HLA-A24 supermotif
e) HLA-B7 supermnotif
f) H LA-B27 supermotif
g) HLA-B44 supermotif
h) HLA-B58 supermotif
i) HLA-B62 supermotif
j) HLA-A1 motif
k) HLA-A3 motif
l) HLA-A11 motif
m) HLA-A24 motif
n) HLA-A2.1 motif
o) HLA-DR-1-4-7 supermotif
p) HLA-DR3 motifs
3. Enhancing Population Coverage of the Vaccine
D. Immune Response Stimulating Peptide Analogs
E. Computer Screening of Protein Sequences from Disease-Related Antigens for Supermotif or Motif Containing Peptides
F. Assays to Detect T-Cell Responses
G. Preparation of Peptides
H. Use of Peptide Epitopes for Evaluating Immune Responses
I. Vaccine Compositions
1. Minigene Vaccines
2. Combinations with Helper Peptides
J. Administration of Vaccines for Therapeutic or Prophylactic Purposes
K. Kits
V. Examples
Chronic infection by hepatitis B virus (HBV) affects at least 5% of the world""s population and is a major cause of cirrhosis and hepatocellular carcinoma (Hoofnagle, J., N. Engl. J. Med. 323:337, 1990; Fields, B. and Knipe, D., In: Fields Virology 2:2137, 1990). The World Health Organization lists hepatitis B as a leading cause of death worldwide, close behind chronic pulmonary disease, and more prevalent than AIDS. Chronic HBV infection can range from an asymptomatic carrier state to continuous hepatocellular necrosis and inflammation, and can lead to hepatocellular carcinoma.
The immune response to HBV is believed to play an important role in controlling hepatitis B infection. A variety of humoral and cellular responses to different regions of the HBV nucleocapsid core and surface antigens have been identified. T cell mediated immunity, particularly involving class I human leukocyte antigen-restricted cytotoxic T lymphocytes (CTL), is believed to be crucial in combatting established HBV infection.
Class I human leukocyte antigen (HLA) molecules are expressed on the surface of almost all nucleated cells. CTL recognize peptide fragments, derived from intracellular processing of various antigens, in the form of a complex with class I HLA molecules. This recognition event then results in the destruction of the cell bearing the HLA-peptide complex directly or the activation of non-destructive mechanisms e.g., the production of interferon, that inhibit viral replication.
Several studies have emphasized the association between self-limiting acute hepatitis and multispecific CTL responses (Penna, A. et al., J. Exp. Med. 174:1565, 1991; Nayersina, R. et al., J. Immunol. 150:4659, 1993). Spontaneous and interferon-related clearance of chronic HBV infection is also associated with the resurgence of a vigorous CTL response (Guidotti, L. G. et al., Proc. Natl. Acad. Sci. USA 91:3764, 1994). In all such cases the CTL responses are polyclonal, and specific for multiple viral proteins including the HBV envelope, core and polymerase antigens. By contrast, in patients with chronic hepatitis, the CTL activity is usually absent or weak, and antigenically restricted.
The crucial role of CTL in resolution of HBV infection has been further underscored by studies using HBV transgenic mice. Adoptive transfer of HBV-specific CTL into mice transgenic for the HBV genome resulted in suppression of virus replication. This effect was primarily mediated by a non-lytic, lymphokine-based mechanism (Guidotti, L. G. et al., Proc. Natl. Acad. Sci. USA 91:3764, 1994; Guidotti, L. G., Guilhot, S., and Chisari, F. V. J. Virol. 68:1265, 1994; Guidotti, L. G. et al., J. Virol. 69:6158, 1995; Gilles, P. N., Fey, G., and Chisari, F. V., J. Virol. 66:3955, 1992).
As is the case for HLA class I restricted responses, HLA class II restricted T cell responses are usually detected in patients with acute hepatitis, and are absent or weak in patients with chronic infection (Chisari, F. V. and Ferrari, C., Annu. Rev. Immunol. 13:29, 1995). HLA Class II responses are tied to activation of helper T cells (HTLs) Helper T lymphocytes, which recognize Class II HLA molecules, may directly contribute to the clearance of HBV infection through the secretion of cytokines which suppress viral replication (Franco, A. et al., J. Immunol. 159:2001, 1997). However, their primary role in disease resolution is believed to be mediated by inducing activation and expansion of virus-specific CTL and B cells.
In view of the heterogeneous immune response observed with HBV infection, induction of a multi-specific cellular immune response directed simultaneously against multiple epitopes appears to be important for the development of an efficacious vaccine against HBV. There is a need to establish vaccine embodiments that elicit immune responses that correspond to responses seen in patients that clear HBV infection. Epitope-based vaccines appear useful.
Upon development of appropriate technology, the use of epitope-based vaccines has several advantages over current vaccines. The epitopes for inclusion in such a vaccine are to be selected from conserved regions of viral or tumor-associated antigens, in order to reduce the likelihood of escape mutants. The advantage of an epitope-based approach over the use of whole antigens is that there is evidence that the immune response to whole antigens is directed largely toward variable regions of the antigen, allowing for immune escape due to mutations. Furthermore, immunosuppressive epitopes that may be present in whole antigens can be avoided with the use of epitope-based vaccines.
Additionally, with an epitope-based vaccine approach, there is an ability to combine selected epitopes (CTL and HTL) and additionally to modify the composition of the epitopes, achieving, for example, enhanced immunogenicity. Accordingly, the immune response can be modulated, as appropriate, for the target disease. Similar engineering of the response is not possible with traditional approaches.
Another major benefit of epitope-based immune-stimulating vaccines is their safety. The possible pathological side effects caused by infectious agents or whole protein antigens, which might have their own intrinsic biological activity, is eliminated.
An epitope-based vaccine also provides the ability to direct and focus an immune response to multiple selected antigens from the same pathogen. Thus, patient-by-patient variability in the immune response to a particular pathogen may be alleviated by inclusion of epitopes from multiple antigens from that pathogen in a vaccine composition. A xe2x80x9cpathogenxe2x80x9d may be an infectious agent or a tumor associated molecule.
However, one of the most formidable obstacles to the development of broadly efficacious epitope-based immunotherapeutics has been the extreme polymorphism of HLA molecules. To date, effective non-genetically biased coverage of a population has been a task of considerable complexity; such coverage has required that epitopes be used specific for HLA molecules corresponding to each individual HLA allele, therefore, impractically large numbers of epitopes would have to be used in order to cover ethnically diverse populations. There has existed a need to develop peptide epitopes that are bound by multiple HLA antigen molecules for use in epitope-based vaccines. The greater the number of HLA antigen molecules bound, the greater the breadth of population coverage by the vaccine.
Furthermore, as described herein in greater detail, a need has existed to modulate peptide binding properties, for example so that peptides that are able to bind to multiple HLA antigens do so with an affinity that will stimulate an immune response. Identification of epitopes restricted by more than one HLA allele at an affinity that correlates with immunogenicity is important to provide thorough population coverage, and to allow the elicitation of responses of sufficient vigor whereby the natural immune responses noted in self-limiting acute hepatitis, or of spontaneous clearance of chronic HBV infection is induced in a diverse segment of the population. Such a response can also target a broad array of epitopes. The technology disclosed herein provides for such favored immune responses.
The information provided in this section is intended to disclose the presently understood state of the art as of the filing date of the present application. Information is included in this section which was generated subsequent to the priority date of this application. Accordingly, background in this section is not intended, in any way, to delineate the priority date for the invention.
This invention applies our knowledge of the mechanisms by which antigen is recognized by T cells, for example, to develop epitope-based vaccines directed towards HBV. More specifically, this application communicates our discovery of specific epitope pharmaceutical compositions and methods of use in the prevention and treatment of HBV infection.
An embodiment of the present invention includes a peptide composition of less than 100 amino acid residues comprising a peptide epitope useful for inducing an immune response against hepatitis B virus (HBV) said epitope (a) having an amino acid sequence of about 8 to about 13 amino acid residues that have at least 65% identity with a native amino acid sequence for HBV, and, (b) binding to at least one MHC class I HLA allele with a dissociation constant of less than about 500 nM. Further, the peptide composition may comprise an amino acid sequence of at least 77% identity, or at least 100% identity with a native HBV amino acid sequence. In a preferred embodiment, the peptide is one of the peptides designated as being from the envelope, polymerase, protein X, or nucleocapsid core regions of HBV. Preferred peptides are described in Tables VI through XVII or XXI.
An additional embodiment of the present invention comprises a composition of less than 100 amino acid residues comprising a peptide epitope useful for inducing an immune response against hepatitis B virus (HBV) said peptide (a) having an amino acid sequence of about 8 to about 13 amino acid residues and (b) bearing one of the HLA supermotifs or motifs set out in Tables I and II. Furthermore, the composition may comprise a peptide wherein the peptide is one of those described in Tables VI through XVII or Table XXI which bear an HLA A1, A2, A3, A24, B7, B27, B44, B58, or B62 supermotif; or an HLA A1, A3, A11, A24, or A2.1 motif or an HLA A*3301, A*3101, A*6801, B*0702, B*3501, B51, B*5301, B*5401 motif.
In one embodiment of a peptide comprising an HLA A2.1 motif, the peptide does not bear an L or M at position 2 and V at the C-terminal position 9 of a 9 amino acid peptide.
An alternative embodiment of the invention comprises an analog of an HBV peptide of less than 100 amino acid residues in length that bears an HLA binding motif, the analog bearing the same HLA binding motif as the peptide but comprising at least one anchor residue that is different from that of the peptide. In a preferred embodiment, said peptide is an analog of a peptide described in Table VI through Table XVII bearing an HLA A1, A2, A3, A24, B7, B27, B44, B58, or B62 supermotif; or an HLA A1, A3, A11, A24, or A2.1 motif or A3301, A3101, A6801, B0702, B3501, B51, B5301, B5401 motif.
Embodiments of the invention further include a composition of less than 100 amino acid residues comprising a peptide epitope useful for inducing an immune response against hepatitis B virus (HBV) said peptide (a) having an amino acid sequence of about 9 to about 25 amino acid residues that have at least 65% identity with a native amino acid sequence for HBV and (b) binding to at least one MHC class II HLA allele with a dissociation constant of less than about 1000 nM. In a preferred embodiment, the composition comprises a peptide that has at least 77%, or, 100% identity with a native HBV amino acid sequence. Further, the composition may comprise a peptide wherein said peptide is one of those peptides described in Table XVIII or Table XIX.
The invention also includes a peptide composition of less than 100 amino acid residues, said composition comprising an epitope useful for inducing an immune response against hepatitis B virus (HBV) said epitope (a) having an amino acid sequence of about 10 to about 20 amino acid residues and (b) bearing one of the class II HLA motifs set out in Table III. In a preferred embodiment, said peptide is one of those peptides described in Table XVIII or XIX.
Additional embodiments of the invention include a composition that comprises an isolated nucleic acid sequence that encodes one of the peptides set out in Tables VI through XIX or XXI or XXIII.
Alternatively, an embodiment of the invention comprises a composition that comprises at least two peptides, at least one of said at least two peptides selected from Tables VI-XIX or XXI or XXIII. In a preferred embodiment, two or more of the at least two peptides are depicted in Tables VI-XIX or XXI or XXIII. The composition may further comprise at least one nucleic acid sequence. In a preferred embodiment each of said at least two peptides are encoded by a nucleic acid sequence, wherein each of the nucleic acid sequences are located on a single vector.
Embodiments of the invention additionally include a peptide composition of less than 100 amino acid residues, said composition comprising an epitope useful for inducing an immune response against HBV, said epitope having at least one of the amino acid sequences set out in Table XXIII.
An alternative modality for defining the peptides in accordance with the invention is to recite the physical properties, such as length; primary, secondary and/or tertiary structure; or charge, which are correlated with binding to a particular allele-specific HLA molecule or group of allele-specific HLA molecules. A further modality for defining peptides is to recite the physical properties of an HLA binding pocket, or properties shared by several allele-specific HLA binding pockets (e.g. pocket configuration and charge distribution) and reciting that the peptide fits and binds to said pocket or pockets.
An additional embodiment of the invention comprises a method for inducing a cytotoxic T cell response to HBV in a mammal comprising administering to said mammal at least one peptide from Tables VI to XIX or Table XXI.
Further embodiments of the invention include a vaccine for treating HBV infection that induces a protective immune response, wherein said vaccine comprises at least one peptide selected from Tables VI to Table XIX or Table XXI in a pharmaceutically acceptable carrier.
Also included as an embodiment of the invention is a vaccine for preventing HBV infection that induces a protective immune response, wherein said vaccine comprises at least one peptide selected from Tables VI to XIX or Table XXI in a pharmaceutically acceptable carrier.
The invention further includes an embodiment comprising a method for inducing a cytotoxic T cell response to HBV in a mammal, comprising administering to said mammal a nucleic acid sequence encoding a peptide selected from Tables VI to XIX or Table XXI.
A further embodiment of the invention comprises a kit for a vaccine for treating or preventing HBV infection, wherein the vaccine induces a protective immune response, said vaccine comprising at least one peptide selected from Tables VI to XIX or Table XXI in a pharmaceutically acceptable carrier and instructions for administration to a patient.
Lastly, the invention includes an embodiment comprising a method for monitoring immunogenic activity of a vaccine for HBV in a patient having a known HLA-type, the method comprising incubating a T lymphocyte sample from the patient with a peptide selected from Tables VI to XIX or Table XXI which binds the product of at least one HLA allele present in said patient, and detecting for the presence of a T lymphocyte that binds to the peptide. In a preferred embodiment, the peptide comprises a tetrameric complex.
As will be apparent from the discussion below, other methods and embodiments are also contemplated. Further, novel synthetic peptides produced by any of the methods described herein are also part of the invention.